JP2011036018A - Protection control monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection control monitoring device in which both the reproducibility of information and the reduction of the amount of information to be stored can be achieved. <P>SOLUTION: The protection control monitoring device comprises a conversion unit for sequentially converting analog data corresponding to the amount of electricity of a power system to digital data and outputting the results as a data sequence, a calculation unit for sequentially calculating difference data indicating a difference between adjacent data in the data sequence and outputting the results as a difference data sequence, a data block generation unit for dividing each of the difference data in the difference data sequence into a plurality of partial data, generating data blocks from the corresponding partial data, and outputting the results as a data block sequence, a compression unit for reversibly compressing the data block sequence; and a storage unit for storing the reversibly compressed data block sequence. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a protection control monitoring device.

  The protection control monitoring device takes in an analog input from the outside and converts it into digital data, and then performs various processes to realize a protection control monitoring function. In addition, the protection control monitoring device has a function of saving the operation state at the time of event occurrence and data of external input, and enables analysis of the state of the power system and device at the time of event occurrence. (For example, refer to Patent Document 1). For this reason, it is desirable to save the data used for the arithmetic processing as it is when the operation state at the time of the event occurrence or the data of the external input is saved.

JP-A-4-69008

  When storing analog input data for a long time, a large amount of storage memory is required. Particularly in the case of a large number of analog input data such as a bus protection relay device, the required capacity increases in proportion to the number of input data. On the other hand, in an embedded system such as a protection control monitoring device, the memory for storing data has a limited capacity, and it may be impossible to store it as it is.

  In such a case, it is generally conceivable to compress the amount of data by applying lossless compression. However, in the case of analog input data, there is a fluctuation of the value due to random noise, so compression may be almost impossible. In addition, the loss of random noise can be greatly reduced by lossy compression. However, with lossy compression, in addition to random noise, necessary information is reduced, and the reproducibility of the stored information may be lost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a protection control monitoring device that can achieve both the reproducibility of information and the reduction of the amount of information to be stored.

  A protection control monitoring device according to an aspect of the present invention includes: a conversion unit that sequentially converts analog data corresponding to the amount of electricity in a power system into digital data and outputs the data as a data string; and between adjacent data in the data string The difference data representing the difference between the difference data sequence is calculated and output as a difference data sequence, and each of the plurality of difference data in the difference data sequence is divided into a plurality of partial data. A data block generation unit that generates a block and outputs the data block sequence, a compression unit that performs lossless compression of the data block sequence, and a storage unit that stores the losslessly compressed data block sequence.

  ADVANTAGE OF THE INVENTION According to this invention, the protection control monitoring apparatus with which the reproducibility of information and reduction of the amount of information to preserve | save was aimed at can be provided.

It is a block diagram showing the protection control monitoring apparatus which concerns on one Embodiment of this invention. It is a schematic diagram showing an example of a bit slice process. It is a schematic diagram showing an example of bit slice reverse processing. It is a flowchart showing the operation | movement procedure of a protection control monitoring apparatus. It is a flowchart showing the operation | movement procedure of a data display apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a protection control monitoring system 100 according to the first embodiment of the present invention. The protection control monitoring system 100 includes a protection control monitoring device (data collection and recording device) 110 and a data display device 150, and collects and displays information when an event occurs in the power system.

  The electric power system is a system of power generation / transformation / transmission / distribution for supplying electric power to consumers. Here, the power transmission lines L1 to L3 are targeted for protection control monitoring by the protection control monitoring system 100 as the power system.

  The occurrence of an event means that the object of protection control monitoring (for example, transmission lines L1 to L3) deviates from the standard state. For example, a short circuit, a ground fault (including a ground fault due to a lightning strike) It means that the current and voltage of L1 to L3 are out of the standard range. For example, if there is a lightning strike on a transmission line, the voltage on that transmission line will be lower than normal and the current will be higher than normal.

  The protection control monitoring device (data collection and recording device) 110 is connected to the sensor SEN and the circuit breaker CB, and protects, controls, and monitors the power system (here, the transmission lines L1 to L3). Accumulate power system data. An example of the protection control monitoring device 110 is a protection relay (protection relay). The protection relay detects a short circuit or ground fault (lightning strike) that has occurred in the power system, and sends a control signal to the circuit breaker so as to select a fault zone and quickly disconnect it from the power system in order to suppress the influence of the influence.

  The protection control monitoring device 110 includes an AD converter 111, a CPU 112, a RAM 113, a ROM 114, an NV memory 115, an I / O 116, and a shutoff instruction unit 117.

  An AD (Analog-Digital) conversion unit 111 inputs a system electric quantity (analog data) from the sensor SEN in time series, converts the data into analog digital, and converts it into digital data of a fixed number of bits (for example, 16 bits). Output as a column. The grid electricity quantity is an analog quantity representing the state of the power system, and can include the current and voltage of the transmission lines L1 to L3. As described above, the AD converter 111 functions as a conversion unit that sequentially converts analog data corresponding to the amount of electricity in the power system into digital data and outputs the data as a data string.

  In principle, grid electricity quantities of different types and measurement locations are AD converted separately from each other. The same applies to the subsequent difference processing, bit slice processing, and compression processing.

  A CPU (Central Processing Unit) 112 performs the following various processes according to a program stored in the ROM 114.

(1) Calculation of amplitude value of system electricity quantity Since the data string represents the system electricity quantity (for example, current and voltage of the transmission lines L1 to L3), it is a sine wave of a predetermined frequency (for example, 50 Hz, 60 Hz). Represents a series change. For this reason, the amplitude value of the system electric quantity (the amplitude of the sine wave) can be calculated by integrating the data string over one cycle of the sine wave or a part thereof (for example, a quarter cycle). . Prior to the calculation of the amplitude value, the temporal variation of the data string is smoothed by digital filter processing, and noise is removed. As described above, the CPU 112 functions as a calculation unit that calculates an amplitude value of a data string (for example, a system electric quantity such as current and voltage).

(2) Event detection (relay operation judgment)
CPU112 detects generation | occurrence | production of the event in an electric power grid | system (for example, power transmission line L1-L3). For example, the occurrence of an event is detected based on the fact that the amplitude value of the grid electricity quantity exceeds a predetermined value. When an event is detected, a trip command for the circuit breaker CB is issued, system electricity amount data is stored in the NV memory 115, and the like.

  However, it is not necessary to execute both the issuance of trip command and the storage of data uniformly. That is, the conditions for issuing the trip command and storing the data can be made different. For example, the data is stored when the amplitude value of the system electricity quantity exceeds the first value, and the trip command is issued when the amplitude value of the system electricity quantity exceeds the second value that is larger than the first value. It is possible.

(3) Relay operation When an event occurs, the CPU 112 issues a trip command to the disconnection instruction unit 117 to operate the circuit breaker CB and electrically disconnect the power transmission lines L1 to L3 (relay operation). As a result, power transmission by the power transmission lines L1 to L3 in which an event such as a lightning strike has occurred is stopped.

(4) Storage of grid electricity quantity data When an event occurs, the CPU 112 saves grid electricity quantity data in the NV memory 115. Prior to this data storage, preprocessing (difference processing, bit slice processing) and data compression processing are executed. By performing the preprocessing before the data compression processing, the data compression efficiency is improved, and it is possible to achieve both the reproducibility of information and the reduction of the amount of information to be stored.

The CPU 112 functions as follows. Details of this will be described later.
・ Calculation unit that sequentially calculates the difference data representing the difference between adjacent data in the data string and outputs it as a difference data string ・ Splitting each of the plurality of difference data in the difference data string into a plurality of partial data A data block generator that generates a data block from a plurality of partial data and outputs it as a data block sequence. A compression unit that reversibly compresses a data block sequence.

A RAM (Random Access Memory) 113 stores calculation results in the CPU 112 and data in the process of calculation.
A ROM (Read Only Memory) 114 stores a program for operating the CPU 112.

   The NV (non-volatile) memory 115 stores analog input data and the like used for relay operation determination before and after the operation so that the information can be retained even when the apparatus is turned off.

  An I / O (Input / Output) 116 is an input / output interface for inputting / outputting data to / from an external device (an external device or a unit in the device). The I / O 116 outputs the data stored in the NV memory 115 to the data display device 150.

  The breaker instruction unit 117 turns on / off the breaker CB according to an instruction from the CPU 112.

  The data display device 150 inputs data stored in the NV memory 115 from the protection control monitoring device 110, analyzes and displays it.

  The data display device 150 includes a CPU 151, a RAM 152, a ROM 153, an I / O 154, and a display device 155.

  A CPU (Central Processing Unit) 151 performs data restoration (data expansion processing, bit slice reverse processing, sum processing), data analysis processing, and display on the display device 155 in accordance with a program stored in the ROM 153. Details of the data restoration will be described later.

A RAM (Random Access Memory) 152 stores calculation results in the CPU 112 and data in the process of calculation.
A ROM (Read Only Memory) 153 stores a program for operating the CPU 151.

The I / O 154 is an input / output interface for inputting / outputting data to / from an external device (an external device or a unit in the device).
The display device 155 is a device that displays the analysis result, for example, a liquid crystal display device.

(Details of grid electricity data storage)
A. Necessity of data compression If the capacity of the NV memory 115 provided in the protection control monitoring device 110 is sufficient for data analysis, the analog input data can be stored as it is. However, when the operation time is prolonged or when it is applied to a model having a large number of analog inputs, the amount of data to be stored may exceed the capacity of the NV memory 115, which may be difficult to store as it is. . For example, when the protection control monitoring device 110 attempts to record a current and voltage waveform at the time of occurrence of an event, the capacity M necessary for recording is expressed by the following equation (1).

M = Va * Vb * Vc * Vd (1)
Va: number of data per second Vb: storage time Vc: number of data to be stored Vd: number of times of storage

  Here, when Va = 2880B (bytes), Vb = 3.3 seconds, Vc = 204 amount, and Vd = 1, M = 1.8 MB, and when the capacity of the NV memory 115 is 1 MB, one event Even data corresponding to can not be saved.

  As described above, when the capacity required for recording does not correspond to the capacity of the NV memory 115, it is generally considered that the data amount is compressed by applying reversible compression. However, in the case of analog input data, there is a fluctuation of the value due to random noise, so compression may be almost impossible. By irreversible compression, it is possible to reduce the amount of data by reducing random noise information. However, with lossy compression, in addition to random noise, necessary information is reduced, and the reproducibility of the stored information may be lost.

B. Data compression method Here, the analog input to the protection control monitoring device 110 is based on the fact that a sine wave corresponding to the system frequency is the main component, and by combining differential processing and bit slice processing as preprocessing for lossless compression. It is possible to improve the data compression efficiency by changing the information density. The details will be described below.

(1) Difference processing The main component of the analog input to the protection control monitoring device 110 is a sine wave corresponding to the system frequency, and the fluctuation of data between adjacent sampling data is small compared to the range of expressible data, The effective bit length can be shortened by taking the difference. A specific example is shown for a case where the analog input is a single sine wave.

The latest sampling data X (n) and the immediately preceding sampling data X (n−1) are expressed by the following equation (2).
X (n) = A * sin (ωn + θ)
X (n−1) = A * sin (ω (n−1) + θ) (2)
A: amplitude value, ω: sampling angle, θ: phase, n: sampling number

When the difference between the latest sampling data X (n) and the immediately preceding sampling data X (n−1) is taken, the following equation (3) is obtained.
X (n) -X (n-1)
= A * sin (ωn + θ) −A * sin (ω (n−1) + θ)
= 2A * sin (ω / 2) * cos (ωn + θ + ω / 2) (3)

The ratio R between the amplitude value A1 after taking the difference and the amplitude value A before taking the difference is expressed by the following equation (4).
R
= A1 / A
= 2A * sin (ω / 2) / A
= 2sin (ω / 2)
≒ ω ... Formula (4)
(When ω is sufficiently small, the approximation of sin (ω) = ω holds)

  From this equation (4), it can be seen that the amplitude value A1 (amplitude value ratio R) after the difference is made smaller according to the sampling angle ω. The amplitude value A1 of the difference of the data with the sampling angle ω of π / 48 is about 1/15 as large as the amplitude value A before taking the difference. This indicates that the upper bits after taking the difference have only information representing the code. Thus, a large data change is held in the upper bits of the difference data, and a finer data change appears in the lower bits. That is, the data of the upper bits has a relatively low information density. Therefore, as will be described later, by dividing the difference data in units of several bits and collecting the upper bit portions, highly efficient compression with a general compression algorithm is possible.

  The sampling data (waveform data) is 16-bit binary data, for example. As described above, the sampling data has a rough pattern in which fine noise overlaps the sine wave. That is, the sampling data includes a portion representing the rough characteristics of the sine wave and a portion representing the fine structure of the data. By taking the difference of the sampling data, it is possible to more clearly distinguish the portion representing the rough feature and the portion representing the fine structure. That is, the upper and lower portions of the difference data more clearly correspond to the portion representing the rough characteristics of the sine wave and the portion representing the fine structure of the data.

  When taking the difference, it is not always necessary to use the immediately preceding sampling data, but as the equation (4) shows, the degree to which the amplitude value becomes small is low. If the frequency of the grid electricity and the sampling timing of the device are completely the same, the difference between the data that is 360 degrees before the electrical angle or the sum of the data that is 180 degrees before is taken. The result is 0 and the amount of information is minimal. However, in practice, the frequency of the grid electricity does not match the sampling timing of the device, and the grid frequency varies depending on the grid status. For this reason, as a result, the data can be more reliably compressed by taking the difference from the immediately preceding sampling data.

(2) Bit slice processing By gathering the upper portions of the difference data (bit slice processing), the continuity of the same pattern (0, 1) can be further enhanced and more efficient compression can be achieved.

FIG. 2 is a schematic diagram illustrating an example of bit slice processing.
In this example, 16-bit data block sequences B1 to B4 are generated from continuous 16-bit data sequences A1 to A4. Each of the data strings A1 to A4 is difference data of sampling data of the grid electricity quantity.

  Each of the data strings A1 to A4 is divided into four 4-bit partial data strings A11 to A14, A21 to A24, A31 to A34, and A41 to A44. The upper 4-bit partial data strings A11 to A41 of the data strings A1 to A4 are collected and reconstructed as one 16-bit data block B1. Similarly, the middle and upper partial data strings A21 to A21, the middle and lower partial data strings A31 to A31, and the lower partial data strings A31 to A31 are also reconstructed as 16-bit data blocks B2 to B4. By this processing, it can be reconstructed into four large blocks B1 to B4 having different information densities without changing the entire data amount.

  The data length of the data string need not be 16 bits, and the number of divisions need not be four. For example, when the number of divisions is 8, a data block is reconstructed every 8 samplings in a partial data string of 2 bits and reconstructed into 8 data blocks having different information densities. Further, the division unit does not need to be equal, and for example, 16-bit data may be divided into 4, 4, and 8 from the upper bits.

  In this way, by adding preprocessing (difference processing and bit slice processing) before compression processing, it is possible to perform highly versatile compression processing without changing the compression algorithm itself.

(3) Compression processing As a compression algorithm after differential processing and bit slice processing, a versatile deflate method (a kind of lossless compression processing) can be used. In this method, overlapping patterns are encoded by run-length encoding typified by the LZ77 algorithm and the encoded data is encoded by a Huffman code.

  In the case of a data string in which 0 or 1 continues, significant compression efficiency can be expected in encoding of a data pattern. Since the upper data block after the differential processing and the bit slicing processing has almost only code information, as a result, it tends to be a data string in which 0 or 1 continues. Therefore, since the data is suitable for the run-length encoding, high compression efficiency is possible.

  Here, the data of the lower bits after performing the difference processing and the bit slicing processing is greatly affected by the random data, so that even if the compression processing is performed, almost no data compression can be expected. For this reason, in order to reduce the amount of operation processing and the capacity of the RAM 113 used for the operation, it is conceivable that the compression processing is not performed on the data block of the lower bits after performing the difference processing and the bit slice processing.

  Specifically, it is conceivable that the data blocks B1 to B3 are subjected to lossless compression processing and the data block B4 is not subjected to compression processing. It is also conceivable that the data blocks B1 and B2 are subjected to lossless compression processing and the data blocks B3 and B4 are not subjected to compression processing. Furthermore, it is also conceivable that only the data block B1 is subjected to lossless compression processing and the data blocks B2 to B4 are not subjected to compression processing. In general, the higher the data block, the easier it becomes a data string in which 0 or 1 continues, and the higher the compression efficiency.

  References on compression algorithms: “A Universal Algorithm for Sequential Data Compression”, JACOB ZIV, FELLOW, IEEE, AND ABRAHAM LEMPEL, MEMBER, IEEE, IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. IT-23, NO. 3, MAY 1977, PP337-343

(4) Data Delivery and Restoration Data compressed data stored in the NV memory 115 itself can be delivered to the data display device 150 and expanded on the data display device 150 side. Further, the compressed data can be transferred to the data display device 150 after being restored to the original data developed in the protection control monitoring device 110.

  Data restoration can be performed by sequentially executing data expansion processing, bit slice reverse processing, and sum processing.

  Data decompression processing is the reverse of data compression processing. Data before compression is restored by decompressing the compressed data.

  Bit slice reverse processing is reverse processing of bit slice processing. As shown in FIG. 3, the original data strings A1 to A4 are restored by performing bit slice processing again on the block data B1 to B4 subjected to the bit slice processing. That is, in this example, the bit slice reverse process is the bit slice process itself.

  The sum processing is processing for calculating the sum between adjacent block data, and is the reverse processing of the difference processing.

  Sampling data (system electrical quantity data) can be reproduced by the above expansion processing, bit slice reverse processing, and sum processing.

(Operation of Protection Control Monitoring System 100)
The operation of the protection control monitoring system 100 will be described.
4 and 5 are flowcharts showing the operation procedure of the protection control monitoring device 110 and the data display device 150, respectively.

A. Operation of Protection Control Monitoring Device 110 (1) Capture of power system data (step S11)
Data of the system electricity quantity from the sensor SEN is sequentially taken into the AD converter 111 and subjected to AD conversion, thereby generating a data string representing a time series change in the system electricity quantity. As described above, grid electricity quantities with different types and measurement locations are AD-converted separately.

(2) Event detection (step S12)
The CPU 112 detects a change in the event. That is, the amplitude value of the grid electricity quantity is compared with a predetermined reference value, and it is determined that an event has occurred when the amplitude value is greater than the reference value. As shown below, in response to the occurrence of an event, grid electricity quantity data is written into the NV memory 115. Prior to this writing, differential processing, bit slicing processing, and data compression processing are performed on the grid electricity data.

(3) Difference processing (step S13)
The difference between the data strings of adjacent system electricity amounts is calculated, and a difference data string is generated.

(4) Bit slice processing (step S14)
Bit slice processing is performed on the difference data string. That is, each difference data string is divided into a plurality of partial data (bits) and rearranged (synthesized) to generate a data block string.

(5) Data compression processing / writing (steps S15 and S16)
A reversible compression process is performed on the generated data block sequence and written to the NV memory 115.

B. Operation of Data Display Device 150 (1) Reading Data (Step S21)
The data display device 150 reads out the data block string written in the NV memory 115 via the I / Os 116 and 154.

(2) Data decompression process (step S22)
The CPU 151 decompresses the read data block sequence to reproduce the data block sequence before the lossless compression process.

(3) Bit slice reverse processing (step S23)
The CPU 151 reproduces the difference data sequence by performing bit slice reverse processing on the decompressed data block sequence. That is, each data block string is divided into a plurality of partial data (bits) and rearranged (synthesized), thereby reproducing the difference data string.

(4) Sum processing (step S24)
The CPU 151 reproduces a data string (power system data) representing a time-series change in the grid electricity quantity by calculating the sum of adjacent data block strings in the decompressed data block string.

(5) Analysis and display of power system data (step S25)
The CPU 151 analyzes the reproduced power system data and causes the display device 155 to display the analysis result.

  As described above, compression efficiency is improved by adding preprocessing (difference processing and bit slice processing) to lossless compression processing for data that has been difficult to compress only with lossless compression processing.

  As a result, it is possible to store in the NV memory 115 information corresponding to a time that could not be stored in the past without changing the capacity of the NV memory 115 itself. Even when long-time data is not required, the data size to be saved per time can be reduced, and the number of recordings can be increased. By increasing the number of times of recording, even if a plurality of events to be recorded occur in a short period of time, it is possible to retain data relating to all the events, and it becomes easier to analyze the operation of the apparatus and verify the operating state of the system.

(Second Embodiment)
When the S / N ratio of the data is not good (for example, when there is no analog input), since there is little sine wave data corresponding to the system frequency, a random data string near 0 is basically obtained. In the case of such input data, taking the difference widens the data distribution and reduces the data compression efficiency. In order to prevent this, the magnitude (amplitude value) of the analog input data at the time of device operation or at the time of change of the output data of the components of the protection control monitoring device 110 is obtained, and if it is below a certain value (predetermined value) By omitting the difference process and the bit slice process, it is possible to prevent the compression efficiency from deteriorating.

  Specifically, when the amplitude value of the data string calculated by the CPU 112 is equal to or less than a predetermined value, the CPU 112 performs the following control. That is, the CPU 112 reversibly compresses this data string and stores the reversibly compressed data string in the NV memory 115.

(Third embodiment)
The occurrence of an event can be associated with the presence or absence of preprocessing.
There may be a correspondence between the occurrence of an event (system fault) and data. For example, lightning causes a large current and a small voltage. Therefore, in response to the occurrence of an event, the current is switched from no preprocessing to preprocessing, and the voltage is switched from preprocessing to no preprocessing.

  Since there are many cases where the analog input is not input due to the operation of the protection control monitoring device 110, the efficiency of data compression is improved by switching between applying lossless compression or preprocessing before and after the device operation. It becomes possible.

Specifically, the CPU 112 performs the following processing.
-The data string is divided into a plurality of partial data strings.
Calculate the amplitude value of each of the partial data strings.
When the calculated amplitude value is equal to or smaller than the predetermined value, the partial data string is reversibly compressed and the reversibly compressed partial data string is stored in the NV memory 115.
If it does in this way, it will become easy to switch separately whether to apply reversible compression or pre-processing to each of current and voltage.

(Fourth embodiment)
In order to deal with special analog input data in which the distribution of the entire data is spread by performing differential processing and bit slice processing, lossless processing is performed after differential processing and bit slice processing. If the input is not suitable for differential processing and bit slicing, the data is compressed even if the input is unsuitable for differential processing and bit slicing. Realize that.

Specifically, the CPU 112 performs the following processing.
-Reversibly compress the difference data string after preprocessing (with preprocessing).
-Reversibly compress the difference data string before preprocessing (no preprocessing).
-Compare the results of lossless compression before and after preprocessing.
Based on the result of this comparison, either the difference data string before or after the preprocessing is reversibly compressed and the reversibly compressed partial data string is stored in the NV memory 115.

(Fifth embodiment)
When the difference between adjacent data is taken and the result becomes negative, the amount of information increases due to an unnecessary 1 being set in bits other than the most significant bit representing the sign. When a sine wave is assumed as an analog input, the amplitude value is compressed to 2 sin (ω / 2) by taking the difference, but all the bits higher than the compressed information length change according to the code. The code information may be one bit, and this is redundant information.

  For example, when 2 and -2 are expressed by 2's complement which is a general numerical expression in 8-bit data, they are [00000010] and [11111110] respectively, but when expressed by a sign and an absolute value, [ [0] + [0000010], [1] + [0000010] and only the difference in code information. When the input data consists only of a sine wave, the difference in sampling data is 2A * sin (ω / 2) cos (ωn + θ + ω / 2) as shown in the first embodiment, where ω represents the sampling angle. Since it is a constant, it becomes a sine wave. In other words, since the data is symmetrical with respect to the origin, the sign bit (1 bit data representing the sign of the difference data) + absolute value data (representing the absolute value of the difference data) as shown in the examples 2 and -2. Information can be reduced by using a representation of (multi-bit data).

  In this case, in the bit slicing process, it is preferable to divide the sign bit and the absolute value data into different partial data strings. That is, the difference data is divided into a partial data string having only sign bits and one or a plurality of partial data strings corresponding to absolute value data, and a data block is generated from the corresponding plurality of partial data.

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention. In the above embodiment, the system data is stored in response to the occurrence of the event, but the system data may be always stored.

DESCRIPTION OF SYMBOLS 100 ... Protection control monitoring system, 110 ... Protection control monitoring apparatus, 111 ... AD converter, 112 ... CPU, 113 ... RAM, 114 ... ROM, 115 ... NV memory, 116 ... I / O, 117 ... Shut-off instruction | indication part, 150 ... Data display device, 151 ... CPU, 152 ... RAM, 153 ... ROM, 154 ... I / O, 155 ... Display device

Claims (7)

A converter that sequentially converts analog data corresponding to the amount of electricity in the power system into digital data and outputs it as a data string;
A calculation unit that sequentially calculates difference data representing a difference between adjacent data in the data string, and outputs the difference data string;
A data block generation unit that divides each of a plurality of difference data in the difference data string into a plurality of partial data, generates a data block from the corresponding plurality of partial data, and outputs the data block as a data block string;
A compression unit for reversibly compressing the data block sequence;
A storage unit for storing the reversibly compressed data block sequence;
A protection control monitoring device comprising: The protection control monitoring according to claim 1, wherein the storage unit stores one or a plurality of data blocks corresponding to one or a plurality of partial data of lower bits in the plurality of partial data without lossless compression. apparatus. A second calculation unit for calculating an amplitude value of the data string;
A control unit for causing the compression unit to reversibly compress the data string and storing the losslessly compressed data string in the storage unit when the calculated amplitude value is a predetermined value or less;
The protection control monitoring apparatus according to claim 1, further comprising: A dividing unit for dividing the data string into a plurality of partial data strings;
A third calculation unit for calculating an amplitude value of each of the plurality of partial data strings;
A control unit for causing the compression unit to reversibly compress the partial data string and storing the losslessly compressed partial data string when the calculated amplitude value is equal to or less than a predetermined value; The protection control monitoring device according to claim 1 or 2, wherein A second compression unit for reversibly compressing the difference data string;
A comparison unit for comparing the results of the lossless compression in the first and second compression units,
The protection control monitoring apparatus according to claim 1, wherein the storage unit stores either the losslessly compressed data block sequence or the losslessly compressed data sequence based on the comparison result. . The difference data is divided into 1-bit data representing the sign of the difference data and multi-bit data representing the absolute value of the difference data.
The protection control monitoring apparatus according to any one of claims 1 to 5, wherein The protection control monitoring apparatus according to claim 1, wherein the compression unit reversibly compresses the data block sequence based on a deflate algorithm.

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